Collins, 29, and Centineo, 22, first raised eyebrows after they were caught out leaving saucy comments to each on Instagram. Recently, Lily commented on a photo of Noah posing shirtless in a chair for his Calvin Klein campaign. She wrote: “I never look that good when I lounge.”
To which the heartthrob responded: "Oh please" and added a flame emoji.
However, sources close to the rumoured item have denied that they're more than friends insisting that they simply share a manager.
The To All The Boys I've Loved Before star also recently directed Collins in a music video called ARTY: Save Me Tonight for Russian musician Arty, in which he also stars.
WATCH: Noah Centineo Says He 'Joined A Gym' To Prep for His Calvin Klein Underwear Photo Shoot